The overall objectives of the total project are (a) to determine how small molecules and their metabolic products affect the stability and function of hemoglobin and other blood proteins and (b) to develop basic biochemical methods that are applicable to the objectives. Small molecules relevant to this project include drugs, industrial chemicals, and environmental pollutants that cause hemolytic anemia and methemoglobinemia. Research goals for the coming year are (1) to determine the mechanism by which the reaction of phenylhydrazine with oxyhemoglobin results in the oxidative cleavage of heme, (2) to compare the effects of phenylhydrazine, ascorbic acid, and hydrogen peroxide on hemoglobin, myoglobin, and synthetic models of hemoglobin, (3) to study the role of superoxide radical ion in oxidative hemolysis in vitro and in vivo, (4) to study the role of the spleen in oxidative hemolysis, and (5) to determine the site of addition of the products of decomposition or metabolism of phenylhydrazine and phenylhydroxylamine to oxidatively denatured hemoglobin.